Time-integrated sampling of fluvial suspended sediment: a simple methodology for small catchments

Fine-grained (< 62.5 <mu>m) suspended sediment transport is a key component of the geochemical flux in most fluvial systems. The highly episodic natur e of suspended sediment transport imposes a significant constraint on the d esign of sampling strategies aimed at characterizing the biogeochemical pro perties of such sediment. A simple sediment sampler, utilizing ambient flow to induce sedimentation by settling, is described. The sampler can be depl oyed unattended in small streams to collect time-integrated suspended sedim ent samples. In laboratory tests involving chemically dispersed sediment, t he sampler collected a maximum of 71% of the input sample mass. However, un der natural conditions, the existence of composite particles or flocs can b e expected to increase significantly the trapping efficiency. Field trials confirmed that the particle size composition and total carbon content of th e sediment collected by the sampler were representative statistically of th e ambient suspended sediment. Copyright (C) 2000 John Wiley & Sons, Ltd.